package com.eshel.mine.view;

import android.content.Context;
import android.graphics.Rect;
import android.support.v4.view.NestedScrollingChild;
import android.support.v4.view.NestedScrollingChildHelper;
import android.support.v4.view.ScrollingView;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.util.Log;
import android.view.FocusFinder;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.animation.AnimationUtils;
import android.widget.FrameLayout;
import android.widget.Scroller;

import java.util.List;
   
/** 
* Reference to ScrollView and HorizontalScrollView 
*/     
public class HVScrollView extends FrameLayout{
    static final int ANIMATED_SCROLL_GAP = 250;
   
    static final float MAX_SCROLL_FACTOR = 0.5f;
    private static final String TAG = "HVScrollView";
    private float lastY;
    private long mLastScroll;
   
    private final Rect mTempRect = new Rect();     
    private Scroller mScroller;

    /** 
     * Flag to indicate that we are moving focus ourselves. This is so the 
     * code that watches for focus changes initiated outside this ScrollView 
     * knows that it does not have to do anything. 
     */     
    private boolean mScrollViewMovedFocus;     
   
    /** 
     * Position of the last motion event. 
     */     
    private float mLastMotionY;     
    private float mLastMotionX;     
   
    /** 
     * True when the layout has changed but the traversal has not come through yet. 
     * Ideally the view hierarchy would keep track of this for us. 
     */     
    private boolean mIsLayoutDirty = true;     
   
    /** 
     * The child to give focus to in the event that a child has requested focus while the 
     * layout is dirty. This prevents the scroll from being wrong if the child has not been 
     * laid out before requesting focus. 
     */     
    private View mChildToScrollTo = null;     
   
    /** 
     * True if the user is currently dragging this ScrollView around. This is 
     * not the same as 'is being flinged', which can be checked by 
     * mScroller.isFinished() (flinging begins when the user lifts his finger). 
     */     
    private boolean mIsBeingDragged = false;     
   
    /** 
     * Determines speed during touch scrolling 
     */     
    private VelocityTracker mVelocityTracker;     
   
    /** 
     * When set to true, the scroll view measure its child to make it fill the currently 
     * visible area. 
     */     
    private boolean mFillViewport;     
   
    /** 
     * Whether arrow scrolling is animated. 
     */     
    private boolean mSmoothScrollingEnabled = true;     
   
    private int mTouchSlop;     
    private int mMinimumVelocity;     
    private int mMaximumVelocity;     
   
    /** 
     * ID of the active pointer. This is used to retain consistency during 
     * drags/flings if multiple pointers are used. 
     */     
    private int mActivePointerId = INVALID_POINTER;     
   
    /** 
     * Sentinel value for no current active pointer. 
     * Used by {@link #mActivePointerId}. 
     */     
    private static final int INVALID_POINTER = -1;     
   
    private boolean mFlingEnabled = true;     
   
    public HVScrollView(Context context) {     
        this(context, null);     
    }     
   
    public HVScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);     
        initScrollView();     
    }     
   
    @Override     
    protected float getTopFadingEdgeStrength() {     
        if (getChildCount() == 0) {     
            return 0.0f;     
        }     
   
        final int length = getVerticalFadingEdgeLength();     
        if (getScrollY() < length) {     
            return getScrollY() / (float) length;     
        }     
   
        return 1.0f;     
    }     
   
    @Override     
    protected float getLeftFadingEdgeStrength() {     
        if (getChildCount() == 0) {     
            return 0.0f;     
        }     
   
        final int length = getHorizontalFadingEdgeLength();     
        if (getScrollX() < length) {     
            return getScrollX() / (float) length;     
        }     
   
        return 1.0f;     
    }     
   
    @Override     
    protected float getRightFadingEdgeStrength() {     
        if (getChildCount() == 0) {     
            return 0.0f;     
        }     
   
        final int length = getHorizontalFadingEdgeLength();     
        final int rightEdge = getWidth() - getPaddingRight();     
        final int span = getChildAt(0).getRight() - getScrollX() - rightEdge;     
        if (span < length) {     
            return span / (float) length;     
        }     
   
        return 1.0f;     
    }     
   
    @Override     
    protected float getBottomFadingEdgeStrength() {     
        if (getChildCount() == 0) {     
            return 0.0f;     
        }     
   
        final int length = getVerticalFadingEdgeLength();     
        final int bottomEdge = getHeight() - getPaddingBottom();     
        final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge;     
        if (span < length) {     
            return span / (float) length;     
        }     
   
        return 1.0f;     
    }     
   
    /** 
     * @return The maximum amount this scroll view will scroll in response to 
     *   an arrow event. 
     */     
     public int getMaxScrollAmountV() {     
        return (int) (MAX_SCROLL_FACTOR * (getBottom() - getTop()));     
    }     
   
    public int getMaxScrollAmountH() {     
        return (int) (MAX_SCROLL_FACTOR * (getRight() - getLeft()));     
    }     
   
   
    private void initScrollView() {
        mScroller = new Scroller(getContext());
        setFocusable(true);
        setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);     
        setWillNotDraw(false);     
        final ViewConfiguration configuration = ViewConfiguration.get(getContext());     
        mTouchSlop = configuration.getScaledTouchSlop();     
        mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();     
        mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
    }     
   
    @Override     
    public void addView(View child) {     
        if (getChildCount() > 0) {     
            throw new IllegalStateException("ScrollView can host only one direct child");     
        }     
   
        super.addView(child);     
    }     
   
    @Override     
    public void addView(View child, int index) {     
        if (getChildCount() > 0) {     
            throw new IllegalStateException("ScrollView can host only one direct child");     
        }     
   
        super.addView(child, index);     
    }     
   
    @Override     
    public void addView(View child, ViewGroup.LayoutParams params) {     
        if (getChildCount() > 0) {     
            throw new IllegalStateException("ScrollView can host only one direct child");     
        }     
   
        super.addView(child, params);     
    }     
   
    @Override     
    public void addView(View child, int index, ViewGroup.LayoutParams params) {     
        if (getChildCount() > 0) {     
            throw new IllegalStateException("ScrollView can host only one direct child");     
        }     
   
        super.addView(child, index, params);     
    }     
   
    /** 
     * @return Returns true this ScrollView can be scrolled 
     */     
    private boolean canScrollV() {     
        View child = getChildAt(0);     
        if (child != null) {     
            int childHeight = child.getHeight();     
            return getHeight() < childHeight + getPaddingTop() + getPaddingBottom();     
        }     
        return false;     
    }     
   
    private boolean canScrollH() {     
        View child = getChildAt(0);     
        if (child != null) {     
            int childWidth = child.getWidth();     
            return getWidth() < childWidth + getPaddingLeft() + getPaddingRight() ;     
        }     
        return false;     
    }     
   
    /** 
     * Indicates whether this ScrollView's content is stretched to fill the viewport. 
     * 
     * @return True if the content fills the viewport, false otherwise. 
     */     
    public boolean isFillViewport() {     
        return mFillViewport;     
    }     
   
    /** 
     * Indicates this ScrollView whether it should stretch its content height to fill 
     * the viewport or not. 
     * 
     * @param fillViewport True to stretch the content's height to the viewport's 
     *        boundaries, false otherwise. 
     */     
    public void setFillViewport(boolean fillViewport) {     
        if (fillViewport != mFillViewport) {     
            mFillViewport = fillViewport;     
            requestLayout();     
        }     
    }     
   
    /** 
     * @return Whether arrow scrolling will animate its transition. 
     */     
    public boolean isSmoothScrollingEnabled() {     
        return mSmoothScrollingEnabled;     
    }     
   
    /** 
     * Set whether arrow scrolling will animate its transition. 
     * @param smoothScrollingEnabled whether arrow scrolling will animate its transition 
     */     
    public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) {     
        mSmoothScrollingEnabled = smoothScrollingEnabled;     
    }     
   
    @Override     
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {     
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);     
   
        if (!mFillViewport) {     
            return;     
        }     
   
        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);     
        final int widthMode = MeasureSpec.getMode(widthMeasureSpec);     
        if (heightMode == MeasureSpec.UNSPECIFIED && widthMode == MeasureSpec.UNSPECIFIED) {     
            return;     
        }     
   
        if (getChildCount() > 0) {     
            final View child = getChildAt(0);     
            int height = getMeasuredHeight();     
            int width = getMeasuredWidth();     
            if (child.getMeasuredHeight() < height || child.getMeasuredWidth() < width) {     
                width -= getPaddingLeft();     
                width -= getPaddingRight();     
                int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY);     
   
                height -= getPaddingTop();     
                height -= getPaddingBottom();     
                int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);     
   
                child.measure(childWidthMeasureSpec, childHeightMeasureSpec);     
            }     
        }     
    }     
    @Override     
    public boolean dispatchKeyEvent(KeyEvent event) {     
        // Let the focused view and/or our descendants get the key first     
        return super.dispatchKeyEvent(event) || executeKeyEvent(event);     
    }     
   
    /** 
     * You can call this function yourself to have the scroll view perform 
     * scrolling from a key event, just as if the event had been dispatched to 
     * it by the view hierarchy. 
     * 
     * @param event The key event to execute. 
     * @return Return true if the event was handled, else false. 
     */     
    public boolean executeKeyEvent(KeyEvent event) {     
        mTempRect.setEmpty();     
   
        boolean handled = false;     
   
        if (event.getAction() == KeyEvent.ACTION_DOWN) {     
            switch (event.getKeyCode()) {     
            case KeyEvent.KEYCODE_DPAD_LEFT:     
                if(canScrollH()){     
                    if (!event.isAltPressed()) {     
                        handled = arrowScrollH(View.FOCUS_LEFT);     
                    } else {     
                        handled = fullScrollH(View.FOCUS_LEFT);     
                    }     
                }     
                break;     
            case KeyEvent.KEYCODE_DPAD_RIGHT:     
                if(canScrollH()){     
                    if (!event.isAltPressed()) {     
                        handled = arrowScrollH(View.FOCUS_RIGHT);     
                    } else {     
                        handled = fullScrollH(View.FOCUS_RIGHT);     
                    }     
                }     
                break;     
            case KeyEvent.KEYCODE_DPAD_UP:     
                if(canScrollV()){     
                    if (!event.isAltPressed()) {     
                        handled = arrowScrollV(View.FOCUS_UP);     
                    } else {     
                        handled = fullScrollV(View.FOCUS_UP);     
                    }     
                }     
                break;     
            case KeyEvent.KEYCODE_DPAD_DOWN:     
                if(canScrollV()){     
                    if (!event.isAltPressed()) {     
                        handled = arrowScrollV(View.FOCUS_DOWN);     
                    } else {     
                        handled = fullScrollV(View.FOCUS_DOWN);     
                    }     
                }     
                break;     
            }     
        }     
        return handled;     
    }     
   
    private boolean inChild(int x, int y) {     
        if (getChildCount() > 0) {     
            final int scrollX = getScrollX();     
            final int scrollY = getScrollY();     
            final View child = getChildAt(0);     
            return !(y < child.getTop() - scrollY     
                    || y >= child.getBottom() - scrollY     
                    || x < child.getLeft() - scrollX     
                    || x >= child.getRight() - scrollX);     
        }     
        return false;     
    }     
   
    @Override     
    public boolean onInterceptTouchEvent(MotionEvent ev) {     
        /* 
         * This method JUST determines whether we want to intercept the motion. 
         * If we return true, onMotionEvent will be called and we do the actual 
         * scrolling there. 
         */     
   
        /* 
         * Shortcut the most recurring case: the user is in the dragging 
         * state and he is moving his finger.  We want to intercept this 
         * motion. 
         */     
        final int action = ev.getAction();     
        if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) {     
            return true;     
        }     
   
        switch (action & MotionEvent.ACTION_MASK) {     
        case MotionEvent.ACTION_MOVE: {
            /*
             * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check 
             * whether the user has moved far enough from his original down touch. 
             */     
   
            /* 
             * Locally do absolute value. mLastMotionY is set to the y value 
             * of the down event. 
             */     
            final int activePointerId = mActivePointerId;     
            if (activePointerId == INVALID_POINTER) {     
                // If we don't have a valid id, the touch down wasn't on content.     
                break;     
            }     
   
            final int pointerIndex = ev.findPointerIndex(activePointerId);     
            final float y = ev.getY(pointerIndex);     
            final int yDiff = (int) Math.abs(y - mLastMotionY);     
            if (yDiff > mTouchSlop) {     
                mIsBeingDragged = true;     
                mLastMotionY = y;     
            }     
            final float x = ev.getX(pointerIndex);     
            final int xDiff = (int) Math.abs(x - mLastMotionX);     
            if (xDiff > mTouchSlop) {     
                mIsBeingDragged = true;     
                mLastMotionX = x;     
            }     
            break;     
        }     
   
        case MotionEvent.ACTION_DOWN: {     
            final float x = ev.getX();     
            final float y = ev.getY();
            lastY = y;
            if (!inChild((int)x, (int) y)) {     
                mIsBeingDragged = false;     
                break;     
            }     
   
            /* 
             * Remember location of down touch. 
             * ACTION_DOWN always refers to pointer index 0. 
             */     
            mLastMotionY = y;     
            mLastMotionX = x;     
            mActivePointerId = ev.getPointerId(0);     
   
            /* 
             * If being flinged and user touches the screen, initiate drag; 
             * otherwise don't.  mScroller.isFinished should be false when 
             * being flinged. 
             */     
            mIsBeingDragged = !mScroller.isFinished();
            break;     
        }     
   
        case MotionEvent.ACTION_CANCEL:     
        case MotionEvent.ACTION_UP:     
            /* Release the drag */     
            mIsBeingDragged = false;     
            mActivePointerId = INVALID_POINTER;
            break;     
        case MotionEvent.ACTION_POINTER_UP:     
            onSecondaryPointerUp(ev);     
            break;     
        }     
   
        /* 
         * The only time we want to intercept motion events is if we are in the 
         * drag mode. 
         */     
        return mIsBeingDragged;     
    }     
   
    @Override     
    public boolean onTouchEvent(MotionEvent ev) {

        if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {     
            // Don't handle edge touches immediately -- they may actually belong to one of our     
            // descendants.     
            return false;     
        }     
   
        if (mVelocityTracker == null) {     
            mVelocityTracker = VelocityTracker.obtain();     
        }     
        mVelocityTracker.addMovement(ev);     
   
        final int action = ev.getAction();     
   
        switch (action & MotionEvent.ACTION_MASK) {     
        case MotionEvent.ACTION_DOWN: {
            final float x = ev.getX();     
            final float y = ev.getY();     
            if (!(mIsBeingDragged = inChild((int) x, (int) y))) {     
                return false;     
            }     
   
            /* 
             * If being flinged and user touches, stop the fling. isFinished 
             * will be false if being flinged. 
             */     
            if (!mScroller.isFinished()) {     
                mScroller.abortAnimation();     
            }     
   
            // Remember where the motion event started     
            mLastMotionY = y;     
            mLastMotionX = x;     
            mActivePointerId = ev.getPointerId(0);
            break;     
        }     
        case MotionEvent.ACTION_MOVE:
            if (mIsBeingDragged) {
                // Scroll to follow the motion event
                final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
                final float y = ev.getY(activePointerIndex);
                final int deltaY = (int) (mLastMotionY - y);
                mLastMotionY = y;

                final float x = ev.getX(activePointerIndex);
                final int deltaX = (int) (mLastMotionX - x);
                mLastMotionX = x;
   
                scrollBy(deltaX, deltaY);     
            }
            break;     
        case MotionEvent.ACTION_UP:      
            if (mIsBeingDragged) {     
                if(mFlingEnabled){     
                    final VelocityTracker velocityTracker = mVelocityTracker;     
                    velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);     
                    int initialVelocitx = (int) velocityTracker.getXVelocity();     
                    int initialVelocity = (int) velocityTracker.getYVelocity();    
//                  int initialVelocitx = (int) velocityTracker.getXVelocity(mActivePointerId);     
//                  int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId);     
   
                    if (getChildCount() > 0) {     
                        if(Math.abs(initialVelocitx) > initialVelocitx || Math.abs(initialVelocity) > mMinimumVelocity) {     
                            fling(-initialVelocitx, -initialVelocity);     
                        }     
   
                    }     
                }     
   
                mActivePointerId = INVALID_POINTER;     
                mIsBeingDragged = false;     
   
                if (mVelocityTracker != null) {     
                    mVelocityTracker.recycle();     
                    mVelocityTracker = null;     
                }     
            }
            break;     
        case MotionEvent.ACTION_CANCEL:     
            if (mIsBeingDragged && getChildCount() > 0) {     
                mActivePointerId = INVALID_POINTER;     
                mIsBeingDragged = false;     
                if (mVelocityTracker != null) {     
                    mVelocityTracker.recycle();     
                    mVelocityTracker = null;     
                }     
            }
            break;     
        case MotionEvent.ACTION_POINTER_UP:     
            onSecondaryPointerUp(ev);     
            break;     
        }     
        return true;     
    }     
   
    private void onSecondaryPointerUp(MotionEvent ev) {     
        final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_ID_MASK) >>     
        MotionEvent.ACTION_POINTER_ID_SHIFT;     
        final int pointerId = ev.getPointerId(pointerIndex);     
        if (pointerId == mActivePointerId) {     
            // This was our active pointer going up. Choose a new     
            // active pointer and adjust accordingly.     
            final int newPointerIndex = pointerIndex == 0 ? 1 : 0;     
            mLastMotionX = ev.getX(newPointerIndex);     
            mLastMotionY = ev.getY(newPointerIndex);     
            mActivePointerId = ev.getPointerId(newPointerIndex);     
            if (mVelocityTracker != null) {     
                mVelocityTracker.clear();     
            }     
        }     
    }    
    /** 
     * <p> 
     * Finds the next focusable component that fits in the specified bounds. 
     * </p> 
     * 
     * @param topFocus look for a candidate is the one at the top of the bounds 
     *                 if topFocus is true, or at the bottom of the bounds if topFocus is 
     *                 false 
     * @param top      the top offset of the bounds in which a focusable must be 
     *                 found 
     * @param bottom   the bottom offset of the bounds in which a focusable must 
     *                 be found 
     * @return the next focusable component in the bounds or null if none can 
     *         be found 
     */     
    private View findFocusableViewInBoundsV(boolean topFocus, int top, int bottom) {     
   
        List<View> focusables = getFocusables(View.FOCUS_FORWARD);     
        View focusCandidate = null;     
   
        /* 
         * A fully contained focusable is one where its top is below the bound's 
         * top, and its bottom is above the bound's bottom. A partially 
         * contained focusable is one where some part of it is within the 
         * bounds, but it also has some part that is not within bounds.  A fully contained 
         * focusable is preferred to a partially contained focusable. 
         */     
        boolean foundFullyContainedFocusable = false;     
   
        int count = focusables.size();     
        for (int i = 0; i < count; i++) {     
            View view = focusables.get(i);     
            int viewTop = view.getTop();     
            int viewBottom = view.getBottom();     
   
            if (top < viewBottom && viewTop < bottom) {     
                /* 
                 * the focusable is in the target area, it is a candidate for 
                 * focusing 
                 */     
   
                final boolean viewIsFullyContained = (top < viewTop) &&     
                (viewBottom < bottom);     
   
                if (focusCandidate == null) {     
                    /* No candidate, take this one */     
                    focusCandidate = view;     
                    foundFullyContainedFocusable = viewIsFullyContained;     
                } else {     
                    final boolean viewIsCloserToBoundary =     
                        (topFocus && viewTop < focusCandidate.getTop()) ||     
                        (!topFocus && viewBottom > focusCandidate     
                                .getBottom());     
   
                    if (foundFullyContainedFocusable) {     
                        if (viewIsFullyContained && viewIsCloserToBoundary) {     
                            /* 
                             * We're dealing with only fully contained views, so 
                             * it has to be closer to the boundary to beat our 
                             * candidate 
                             */     
                            focusCandidate = view;     
                        }     
                    } else {     
                        if (viewIsFullyContained) {     
                            /* Any fully contained view beats a partially contained view */     
                            focusCandidate = view;     
                            foundFullyContainedFocusable = true;     
                        } else if (viewIsCloserToBoundary) {     
                            /* 
                             * Partially contained view beats another partially 
                             * contained view if it's closer 
                             */     
                            focusCandidate = view;     
                        }     
                    }     
                }     
            }     
        }     
   
        return focusCandidate;     
    }     
   
    private View findFocusableViewInBoundsH(boolean leftFocus, int left, int right) {     
   
        List<View> focusables = getFocusables(View.FOCUS_FORWARD);     
        View focusCandidate = null;     
   
        /* 
         * A fully contained focusable is one where its left is below the bound's 
         * left, and its right is above the bound's right. A partially 
         * contained focusable is one where some part of it is within the 
         * bounds, but it also has some part that is not within bounds.  A fully contained 
         * focusable is preferred to a partially contained focusable. 
         */     
        boolean foundFullyContainedFocusable = false;     
   
        int count = focusables.size();     
        for (int i = 0; i < count; i++) {     
            View view = focusables.get(i);     
            int viewLeft = view.getLeft();     
            int viewRight = view.getRight();     
   
            if (left < viewRight && viewLeft < right) {     
                /* 
                 * the focusable is in the target area, it is a candidate for 
                 * focusing 
                 */     
   
                final boolean viewIsFullyContained = (left < viewLeft) &&     
                (viewRight < right);     
   
                if (focusCandidate == null) {     
                    /* No candidate, take this one */     
                    focusCandidate = view;     
                    foundFullyContainedFocusable = viewIsFullyContained;     
                } else {     
                    final boolean viewIsCloserToBoundary =     
                        (leftFocus && viewLeft < focusCandidate.getLeft()) ||     
                        (!leftFocus && viewRight > focusCandidate.getRight());     
   
                    if (foundFullyContainedFocusable) {     
                        if (viewIsFullyContained && viewIsCloserToBoundary) {     
                            /* 
                             * We're dealing with only fully contained views, so 
                             * it has to be closer to the boundary to beat our 
                             * candidate 
                             */     
                            focusCandidate = view;     
                        }     
                    } else {     
                        if (viewIsFullyContained) {     
                            /* Any fully contained view beats a partially contained view */     
                            focusCandidate = view;     
                            foundFullyContainedFocusable = true;     
                        } else if (viewIsCloserToBoundary) {     
                            /* 
                             * Partially contained view beats another partially 
                             * contained view if it's closer 
                             */     
                            focusCandidate = view;     
                        }     
                    }     
                }     
            }     
        }     
   
        return focusCandidate;     
    }     
   
    /** 
     * <p>Handles scrolling in response to a "home/end" shortcut press. This 
     * method will scroll the view to the top or bottom and give the focus 
     * to the topmost/bottommost component in the new visible area. If no 
     * component is a good candidate for focus, this scrollview reclaims the 
     * focus.</p> 
     * 
     * @param direction the scroll direction: {@link View#FOCUS_UP}
     *                  to go the top of the view or 
     *                  {@link View#FOCUS_DOWN} to go the bottom
     * @return true if the key event is consumed by this method, false otherwise 
     */     
    public boolean fullScrollV(int direction) {     
        boolean down = direction == View.FOCUS_DOWN;     
        int height = getHeight();     
   
        mTempRect.top = 0;     
        mTempRect.bottom = height;     
   
        if (down) {     
            int count = getChildCount();     
            if (count > 0) {     
                View view = getChildAt(count - 1);     
                mTempRect.bottom = view.getBottom();     
                mTempRect.top = mTempRect.bottom - height;     
            }     
        }     
   
        return scrollAndFocusV(direction, mTempRect.top, mTempRect.bottom);     
    }     
   
    public boolean fullScrollH(int direction) {     
        boolean right = direction == View.FOCUS_RIGHT;     
        int width = getWidth();     
   
        mTempRect.left = 0;     
        mTempRect.right = width;     
   
        if (right) {     
            int count = getChildCount();     
            if (count > 0) {     
                View view = getChildAt(0);     
                mTempRect.right = view.getRight();     
                mTempRect.left = mTempRect.right - width;     
            }     
        }     
   
        return scrollAndFocusH(direction, mTempRect.left, mTempRect.right);     
    }     
   
    /** 
     * <p>Scrolls the view to make the area defined by <code>top</code> and 
     * <code>bottom</code> visible. This method attempts to give the focus 
     * to a component visible in this area. If no component can be focused in 
     * the new visible area, the focus is reclaimed by this scrollview.</p> 
     * 
     * @param direction the scroll direction: {@link View#FOCUS_UP}
     *                  to go upward 
     *                  {@link View#FOCUS_DOWN} to downward
     * @param top       the top offset of the new area to be made visible 
     * @param bottom    the bottom offset of the new area to be made visible 
     * @return true if the key event is consumed by this method, false otherwise 
     */     
    private boolean scrollAndFocusV(int direction, int top, int bottom) {     
        boolean handled = true;     
   
        int height = getHeight();     
        int containerTop = getScrollY();     
        int containerBottom = containerTop + height;     
        boolean up = direction == View.FOCUS_UP;     
   
        View newFocused = findFocusableViewInBoundsV(up, top, bottom);     
        if (newFocused == null) {     
            newFocused = this;     
        }     
   
        if (top >= containerTop && bottom <= containerBottom) {     
            handled = false;     
        } else {     
            int delta = up ? (top - containerTop) : (bottom - containerBottom);     
            doScrollY(delta);     
        }     
   
        if (newFocused != findFocus() && newFocused.requestFocus(direction)) {     
            mScrollViewMovedFocus = true;     
            mScrollViewMovedFocus = false;     
        }     
   
        return handled;     
    }     
   
    private boolean scrollAndFocusH(int direction, int left, int right) {     
        boolean handled = true;     
   
        int width = getWidth();     
        int containerLeft = getScrollX();     
        int containerRight = containerLeft + width;     
        boolean goLeft = direction == View.FOCUS_LEFT;     
   
        View newFocused = findFocusableViewInBoundsH(goLeft, left, right);     
        if (newFocused == null) {     
            newFocused = this;     
        }     
   
        if (left >= containerLeft && right <= containerRight) {     
            handled = false;     
        } else {     
            int delta = goLeft ? (left - containerLeft) : (right - containerRight);     
            doScrollX(delta);     
        }     
   
        if (newFocused != findFocus() && newFocused.requestFocus(direction)) {     
            mScrollViewMovedFocus = true;     
            mScrollViewMovedFocus = false;     
        }     
   
        return handled;     
    }     
   
    /** 
     * Handle scrolling in response to an up or down arrow click. 
     * 
     * @param direction The direction corresponding to the arrow key that was 
     *                  pressed 
     * @return True if we consumed the event, false otherwise 
     */     
    public boolean arrowScrollV(int direction) {     
   
        View currentFocused = findFocus();     
        if (currentFocused == this) currentFocused = null;     
   
        View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);     
   
        final int maxJump = getMaxScrollAmountV();     
   
        if (nextFocused != null && isWithinDeltaOfScreenV(nextFocused, maxJump, getHeight())) {     
            nextFocused.getDrawingRect(mTempRect);     
            offsetDescendantRectToMyCoords(nextFocused, mTempRect);     
            int scrollDelta = computeScrollDeltaToGetChildRectOnScreenV(mTempRect);     
            doScrollY(scrollDelta);     
            nextFocused.requestFocus(direction);     
        } else {     
            // no new focus     
            int scrollDelta = maxJump;     
   
            if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) {     
                scrollDelta = getScrollY();     
            } else if (direction == View.FOCUS_DOWN) {     
                if (getChildCount() > 0) {     
                    int daBottom = getChildAt(0).getBottom();     
   
                    int screenBottom = getScrollY() + getHeight();     
   
                    if (daBottom - screenBottom < maxJump) {     
                        scrollDelta = daBottom - screenBottom;     
                    }     
                }     
            }     
            if (scrollDelta == 0) {     
                return false;     
            }     
            doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta);     
        }     
   
        if (currentFocused != null && currentFocused.isFocused()     
                && isOffScreenV(currentFocused)) {     
            // previously focused item still has focus and is off screen, give     
            // it up (take it back to ourselves)     
            // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are     
            // sure to     
            // get it)     
            final int descendantFocusability = getDescendantFocusability();  // save     
            setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);     
            requestFocus();     
            setDescendantFocusability(descendantFocusability);  // restore     
        }     
        return true;     
    }     
   
    public boolean arrowScrollH(int direction) {     
   
        View currentFocused = findFocus();     
        if (currentFocused == this) currentFocused = null;     
   
        View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);     
   
        final int maxJump = getMaxScrollAmountH();     
   
        if (nextFocused != null && isWithinDeltaOfScreenH(nextFocused, maxJump)) {     
            nextFocused.getDrawingRect(mTempRect);     
            offsetDescendantRectToMyCoords(nextFocused, mTempRect);     
            int scrollDelta = computeScrollDeltaToGetChildRectOnScreenH(mTempRect);     
            doScrollX(scrollDelta);     
            nextFocused.requestFocus(direction);     
        } else {     
            // no new focus     
            int scrollDelta = maxJump;     
   
            if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) {     
                scrollDelta = getScrollX();     
            } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) {     
   
                int daRight = getChildAt(0).getRight();     
   
                int screenRight = getScrollX() + getWidth();     
   
                if (daRight - screenRight < maxJump) {     
                    scrollDelta = daRight - screenRight;     
                }     
            }     
            if (scrollDelta == 0) {     
                return false;     
            }     
            doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta);     
        }     
   
        if (currentFocused != null && currentFocused.isFocused()     
                && isOffScreenH(currentFocused)) {     
            // previously focused item still has focus and is off screen, give     
            // it up (take it back to ourselves)     
            // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are     
            // sure to     
            // get it)     
            final int descendantFocusability = getDescendantFocusability();  // save     
            setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);     
            requestFocus();     
            setDescendantFocusability(descendantFocusability);  // restore     
        }     
        return true;     
    }   
    /** 
     * @return whether the descendant of this scroll view is scrolled off 
     *  screen. 
     */     
    private boolean isOffScreenV(View descendant) {     
        return !isWithinDeltaOfScreenV(descendant, 0, getHeight());     
    }     
   
    private boolean isOffScreenH(View descendant) {     
        return !isWithinDeltaOfScreenH(descendant, 0);     
    }     
   
    /** 
     * @return whether the descendant of this scroll view is within delta 
     *  pixels of being on the screen. 
     */     
    private boolean isWithinDeltaOfScreenV(View descendant, int delta, int height) {     
        descendant.getDrawingRect(mTempRect);     
        offsetDescendantRectToMyCoords(descendant, mTempRect);     
   
        return (mTempRect.bottom + delta) >= getScrollY()     
        && (mTempRect.top - delta) <= (getScrollY() + height);     
    }     
   
    private boolean isWithinDeltaOfScreenH(View descendant, int delta) {     
        descendant.getDrawingRect(mTempRect);     
        offsetDescendantRectToMyCoords(descendant, mTempRect);     
   
        return (mTempRect.right + delta) >= getScrollX()     
        && (mTempRect.left - delta) <= (getScrollX() + getWidth());     
    }     
   
    /** 
     * Smooth scroll by a Y delta 
     * 
     * @param delta the number of pixels to scroll by on the Y axis 
     */     
    private void doScrollY(int delta) {     
        if (delta != 0) {     
            if (mSmoothScrollingEnabled) {     
                smoothScrollBy(0, delta);     
            } else {     
                scrollBy(0, delta);     
            }     
        }     
    }     
   
    private void doScrollX(int delta) {     
        if (delta != 0) {     
            if (mSmoothScrollingEnabled) {     
                smoothScrollBy(delta, 0);     
            } else {     
                scrollBy(delta, 0);     
            }     
        }     
    }     
   
    /** 
     * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. 
     * 
     * @param dx the number of pixels to scroll by on the X axis 
     * @param dy the number of pixels to scroll by on the Y axis 
     */     
    public void smoothScrollBy(int dx, int dy) {     
        if (getChildCount() == 0) {     
            // Nothing to do.     
            return;     
        }     
        long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll;     
        if (duration > ANIMATED_SCROLL_GAP) {     
            final int height = getHeight() - getPaddingBottom() - getPaddingTop();     
            final int bottom = getChildAt(0).getHeight();     
            final int maxY = Math.max(0, bottom - height);     
            final int scrollY = getScrollY();     
            dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY;     
   
            final int width = getWidth() - getPaddingRight() - getPaddingLeft();     
            final int right = getChildAt(0).getWidth();     
            final int maxX = Math.max(0, right - width);     
            final int scrollX = getScrollX();     
            dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX;     
   
            mScroller.startScroll(scrollX, scrollY, dx, dy);     
            invalidate();     
        } else {     
            if (!mScroller.isFinished()) {     
                mScroller.abortAnimation();     
            }     
            scrollBy(dx, dy);     
        }     
        mLastScroll = AnimationUtils.currentAnimationTimeMillis();     
    }     
   
    /** 
     * Like {@link #scrollTo}, but scroll smoothly instead of immediately. 
     * 
     * @param x the position where to scroll on the X axis 
     * @param y the position where to scroll on the Y axis 
     */     
    public final void smoothScrollTo(int x, int y) {     
        smoothScrollBy(x - getScrollX(), y - getScrollY());     
    }     
   
    /** 
     * <p>The scroll range of a scroll view is the overall height of all of its 
     * children.</p> 
     */     
    @Override
    public int computeVerticalScrollRange() {
        final int count = getChildCount();
        final int contentHeight = getHeight() - getPaddingBottom() - getPaddingTop();
        if (count == 0) {
            return contentHeight;
        }

        return getChildAt(0).getBottom();
    }
   
    @Override
    public int computeHorizontalScrollRange() {
        final int count = getChildCount();
        final int contentWidth = getWidth() - getPaddingLeft() - getPaddingRight();
        if (count == 0) {
            return contentWidth;
        }

        return getChildAt(0).getRight();
    }     
   
    @Override
    public int computeVerticalScrollOffset() {
        return Math.max(0, super.computeVerticalScrollOffset());
    }

    @Override
    public int computeVerticalScrollExtent() {
        return super.computeVerticalScrollExtent();
    }

    @Override     
    public int computeHorizontalScrollOffset() {
        return super.computeHorizontalScrollOffset();
    }

    @Override
    public int computeHorizontalScrollExtent() {
        return super.computeHorizontalScrollExtent();
    }

    @Override     
    protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) {     
        int childWidthMeasureSpec;     
        int childHeightMeasureSpec;     
   
        childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);     
   
        childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);     
   
        child.measure(childWidthMeasureSpec, childHeightMeasureSpec);     
    }     
   
    @Override     
    protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed,     
            int parentHeightMeasureSpec, int heightUsed) {     
        final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();     
   
        final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(     
                lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED);     
        final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(     
                lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED);     
   
        child.measure(childWidthMeasureSpec, childHeightMeasureSpec);     
    }     
   
    @Override     
    public void computeScroll() {     
        if (mScroller.computeScrollOffset()) {     
            // This is called at drawing time by ViewGroup.  We don't want to     
            // re-show the scrollbars at this point, which scrollTo will do,     
            // so we replicate most of scrollTo here.     
            //     
            //         It's a little odd to call onScrollChanged from inside the drawing.     
            //     
            //         It is, except when you remember that computeScroll() is used to     
            //         animate scrolling. So unless we want to defer the onScrollChanged()     
            //         until the end of the animated scrolling, we don't really have a     
            //         choice here.     
            //     
            //         I agree.  The alternative, which I think would be worse, is to post     
            //         something and tell the subclasses later.  This is bad because there     
            //         will be a window where mScrollX/Y is different from what the app     
            //         thinks it is.     
            //     
            int x = mScroller.getCurrX();     
            int y = mScroller.getCurrY();     
   
            if (getChildCount() > 0) {     
                View child = getChildAt(0);     
                x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth());     
                y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight());     
                super.scrollTo(x, y);     
            }     
            awakenScrollBars();     
   
            // Keep on drawing until the animation has finished.     
            postInvalidate();     
        }     
    }     
   
    /** 
     * Scrolls the view to the given child. 
     * 
     * @param child the View to scroll to 
     */     
    private void scrollToChild(View child) {     
        child.getDrawingRect(mTempRect);     
   
        /* Offset from child's local coordinates to ScrollView coordinates */     
        offsetDescendantRectToMyCoords(child, mTempRect);     
   
        int scrollDeltaV = computeScrollDeltaToGetChildRectOnScreenV(mTempRect);     
        int scrollDeltaH = computeScrollDeltaToGetChildRectOnScreenH(mTempRect);     
   
        if (scrollDeltaH != 0 || scrollDeltaV != 0) {     
            scrollBy(scrollDeltaH, scrollDeltaV);     
        }     
    }     
   
    /** 
     * If rect is off screen, scroll just enough to get it (or at least the 
     * first screen size chunk of it) on screen. 
     * 
     * @param rect      The rectangle. 
     * @param immediate True to scroll immediately without animation 
     * @return true if scrolling was performed 
     */     
    private boolean scrollToChildRect(Rect rect, boolean immediate) {     
        final int deltaV = computeScrollDeltaToGetChildRectOnScreenV(rect);     
        final int deltaH = computeScrollDeltaToGetChildRectOnScreenH(rect);     
        final boolean scroll = deltaH != 0 || deltaV != 0;     
        if (scroll) {     
            if (immediate) {     
                scrollBy(deltaH, deltaV);     
            } else {     
                smoothScrollBy(deltaH, deltaV);     
            }     
        }     
        return scroll;     
    }   
    /** 
     * Compute the amount to scroll in the Y direction in order to get 
     * a rectangle completely on the screen (or, if taller than the screen, 
     * at least the first screen size chunk of it). 
     * 
     * @param rect The rect. 
     * @return The scroll delta. 
     */     
    protected int computeScrollDeltaToGetChildRectOnScreenV(Rect rect) {     
        if (getChildCount() == 0) return 0;     
   
        int height = getHeight();     
        int screenTop = getScrollY();     
        int screenBottom = screenTop + height;     
   
        int fadingEdge = getVerticalFadingEdgeLength();     
   
        // leave room for top fading edge as long as rect isn't at very top     
        if (rect.top > 0) {     
            screenTop += fadingEdge;     
        }     
   
        // leave room for bottom fading edge as long as rect isn't at very bottom     
        if (rect.bottom < getChildAt(0).getHeight()) {     
            screenBottom -= fadingEdge;     
        }     
   
        int scrollYDelta = 0;     
   
        if (rect.bottom > screenBottom && rect.top > screenTop) {     
            // need to move down to get it in view: move down just enough so     
            // that the entire rectangle is in view (or at least the first     
            // screen size chunk).     
   
            if (rect.height() > height) {     
                // just enough to get screen size chunk on     
                scrollYDelta += (rect.top - screenTop);     
            } else {     
                // get entire rect at bottom of screen     
                scrollYDelta += (rect.bottom - screenBottom);     
            }     
   
            // make sure we aren't scrolling beyond the end of our content     
            int bottom = getChildAt(0).getBottom();     
            int distanceToBottom = bottom - screenBottom;     
            scrollYDelta = Math.min(scrollYDelta, distanceToBottom);     
   
        } else if (rect.top < screenTop && rect.bottom < screenBottom) {     
            // need to move up to get it in view: move up just enough so that     
            // entire rectangle is in view (or at least the first screen     
            // size chunk of it).     
   
            if (rect.height() > height) {     
                // screen size chunk     
                scrollYDelta -= (screenBottom - rect.bottom);     
            } else {     
                // entire rect at top     
                scrollYDelta -= (screenTop - rect.top);     
            }     
   
            // make sure we aren't scrolling any further than the top our content     
            scrollYDelta = Math.max(scrollYDelta, -getScrollY());     
        }     
        return scrollYDelta;     
    }     
   
    protected int computeScrollDeltaToGetChildRectOnScreenH(Rect rect) {     
        if (getChildCount() == 0) return 0;     
   
        int width = getWidth();     
        int screenLeft = getScrollX();     
        int screenRight = screenLeft + width;     
   
        int fadingEdge = getHorizontalFadingEdgeLength();     
   
        // leave room for left fading edge as long as rect isn't at very left     
        if (rect.left > 0) {     
            screenLeft += fadingEdge;     
        }     
   
        // leave room for right fading edge as long as rect isn't at very right     
        if (rect.right < getChildAt(0).getWidth()) {     
            screenRight -= fadingEdge;     
        }     
   
        int scrollXDelta = 0;     
   
        if (rect.right > screenRight && rect.left > screenLeft) {     
            // need to move right to get it in view: move right just enough so     
            // that the entire rectangle is in view (or at least the first     
            // screen size chunk).     
   
            if (rect.width() > width) {     
                // just enough to get screen size chunk on     
                scrollXDelta += (rect.left - screenLeft);     
            } else {     
                // get entire rect at right of screen     
                scrollXDelta += (rect.right - screenRight);     
            }     
   
            // make sure we aren't scrolling beyond the end of our content     
            int right = getChildAt(0).getRight();     
            int distanceToRight = right - screenRight;     
            scrollXDelta = Math.min(scrollXDelta, distanceToRight);     
   
        } else if (rect.left < screenLeft && rect.right < screenRight) {     
            // need to move right to get it in view: move right just enough so that     
            // entire rectangle is in view (or at least the first screen     
            // size chunk of it).     
   
            if (rect.width() > width) {     
                // screen size chunk     
                scrollXDelta -= (screenRight - rect.right);     
            } else {     
                // entire rect at left     
                scrollXDelta -= (screenLeft - rect.left);     
            }     
   
            // make sure we aren't scrolling any further than the left our content     
            scrollXDelta = Math.max(scrollXDelta, -getScrollX());     
        }     
        return scrollXDelta;     
    }     
   
    @Override     
    public void requestChildFocus(View child, View focused) {     
        if (!mScrollViewMovedFocus) {     
            if (!mIsLayoutDirty) {     
                scrollToChild(focused);     
            } else {     
                // The child may not be laid out yet, we can't compute the scroll yet     
                mChildToScrollTo = focused;     
            }     
        }     
        super.requestChildFocus(child, focused);     
    }     
   
   
    /** 
     * When looking for focus in children of a scroll view, need to be a little 
     * more careful not to give focus to something that is scrolled off screen. 
     * 
     * This is more expensive than the default {@link ViewGroup}
     * implementation, otherwise this behavior might have been made the default. 
     */     
    @Override     
    protected boolean onRequestFocusInDescendants(int direction,     
            Rect previouslyFocusedRect) {     
   
        // convert from forward / backward notation to up / down / left / right     
        // (ugh).     
        // TODO: FUCK     
        //        if (direction == View.FOCUS_FORWARD) {     
        //            direction = View.FOCUS_RIGHT;     
        //        } else if (direction == View.FOCUS_BACKWARD) {     
        //            direction = View.FOCUS_LEFT;     
        //        }     
   
        final View nextFocus = previouslyFocusedRect == null ?     
                FocusFinder.getInstance().findNextFocus(this, null, direction) :     
                    FocusFinder.getInstance().findNextFocusFromRect(this,     
                            previouslyFocusedRect, direction);     
   
                if (nextFocus == null) {     
                    return false;     
                }     
   
                //        if (isOffScreenH(nextFocus)) {     
                    //            return false;     
                //        }     
   
                return nextFocus.requestFocus(direction, previouslyFocusedRect);     
    }       
   
    @Override     
    public boolean requestChildRectangleOnScreen(View child, Rect rectangle,     
            boolean immediate) {     
        // offset into coordinate space of this scroll view     
        rectangle.offset(child.getLeft() - child.getScrollX(),     
                child.getTop() - child.getScrollY());     
   
        return scrollToChildRect(rectangle, immediate);     
    }     
   
    @Override     
    public void requestLayout() {     
        mIsLayoutDirty = true;     
        super.requestLayout();     
    }     
   
    @Override     
    protected void onLayout(boolean changed, int l, int t, int r, int b) {     
        super.onLayout(changed, l, t, r, b);     
        mIsLayoutDirty = false;     
        // Give a child focus if it needs it      
        if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) {     
            scrollToChild(mChildToScrollTo);     
        }     
        mChildToScrollTo = null;     
   
        // Calling this with the present values causes it to re-clam them     
        scrollTo(getScrollX(), getScrollY());     
    }     
   
    @Override     
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {     
        super.onSizeChanged(w, h, oldw, oldh);     
   
        View currentFocused = findFocus();     
        if (null == currentFocused || this == currentFocused)     
            return;     
   
        // If the currently-focused view was visible on the screen when the     
        // screen was at the old height, then scroll the screen to make that     
        // view visible with the new screen height.     
        if (isWithinDeltaOfScreenV(currentFocused, 0, oldh)) {     
            currentFocused.getDrawingRect(mTempRect);     
            offsetDescendantRectToMyCoords(currentFocused, mTempRect);     
            int scrollDelta = computeScrollDeltaToGetChildRectOnScreenV(mTempRect);     
            doScrollY(scrollDelta);     
        }     
   
        final int maxJump = getRight() - getLeft();     
        if (isWithinDeltaOfScreenH(currentFocused, maxJump)) {     
            currentFocused.getDrawingRect(mTempRect);     
            offsetDescendantRectToMyCoords(currentFocused, mTempRect);     
            int scrollDelta = computeScrollDeltaToGetChildRectOnScreenH(mTempRect);     
            doScrollX(scrollDelta);     
        }     
    }         
   
    /** 
     * Return true if child is an descendant of parent, (or equal to the parent). 
     */     
    private boolean isViewDescendantOf(View child, View parent) {     
        if (child == parent) {     
            return true;     
        }     
   
        final ViewParent theParent = child.getParent();     
        return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent);     
    }         
   
    /** 
     * Fling the scroll view 
     * 
     * @param velocityY The initial velocity in the Y direction. Positive 
     *                  numbers mean that the finger/cursor is moving down the screen, 
     *                  which means we want to scroll towards the top. 
     */     
    public void fling(int velocityX, int velocityY) {     
        if (getChildCount() > 0) {     
            int width = getWidth() - getPaddingRight() - getPaddingLeft();     
            int right = getChildAt(0).getWidth();     
   
            int height = getHeight() - getPaddingBottom() - getPaddingTop();     
            int bottom = getChildAt(0).getHeight();     
   
            mScroller.fling(getScrollX(), getScrollY(), velocityX, velocityY,      
                    0, Math.max(0, right - width),      
                    0, Math.max(0, bottom - height));     
   
            //            final boolean movingDown = velocityX > 0 || velocityY > 0;     
            //         
            //            View newFocused =     
            //                    findFocusableViewInMyBoundsV(movingDown, mScroller.getFinalY(), findFocus());     
            //            if (newFocused == null) {     
            //                newFocused = this;     
            //            }     
            //         
            //            if (newFocused != findFocus()     
            //                    && newFocused.requestFocus(movingDown ? View.FOCUS_DOWN : View.FOCUS_UP)) {     
            //                mScrollViewMovedFocus = true;     
            //                mScrollViewMovedFocus = false;     
            //            }     
   
            invalidate();     
        }     
    }     
   
    /** 
     * {@inheritDoc} 
     * 
     * <p>This version also clamps the scrolling to the bounds of our child. 
     */     
    @Override     
    public void scrollTo(int x, int y) {     
        // we rely on the fact the View.scrollBy calls scrollTo.     
        if (getChildCount() > 0) {     
            View child = getChildAt(0);     
            x = clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth());     
            y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight());     
            if (x != getScrollX() || y != getScrollY()) {     
                super.scrollTo(x, y);     
            }     
        }     
    }     
   
    private int clamp(int n, int my, int child) {     
        if (my >= child || n < 0) {     
            /* my >= child is this case: 
             *                    |--------------- me ---------------| 
             *     |------ child ------| 
             * or 
             *     |--------------- me ---------------| 
             *            |------ child ------| 
             * or 
             *     |--------------- me ---------------| 
             *                                  |------ child ------| 
             * 
             * n < 0 is this case: 
             *     |------ me ------| 
             *                    |-------- child --------| 
             *     |-- mScrollX --| 
             */     
            return 0;     
        }     
        if ((my+n) > child) {     
            /* this case: 
             *                    |------ me ------| 
             *     |------ child ------| 
             *     |-- mScrollX --| 
             */     
            return child-my;     
        }     
        return n;     
    }     
   
    public boolean isFlingEnabled() {     
        return mFlingEnabled;     
    }     
   
    public void setFlingEnabled(boolean flingEnabled) {     
        this.mFlingEnabled = flingEnabled;     
    }

}